Exciting news: @AnthropicAI's Claude Opus 5 (Max) is #2# in Agent Arena, with Opus 5 (High) right behind at #3#, based on over 7K real-world agentic sessions. A strong debut: it slots in just below #1# Fable 5, and ahead of GPT-5.6 Sol (xHigh). Opus 5 Max is #2# with a net-improvement of 11.88%, and is #1# across both Confirmed Success and Praise vs Complaint signals. The default Opus 5 (High) is #3# with net-improvement of 11.73%, and by signal is #3# in Praise vs Complaint and #4# in Confirmed Success. In Agent Arena, we measure models on millions of real-world, long-horizon agentic tasks from a global community of users. Models can access web search, filesystem, and terminal tools to complete complex workflows. The leaderboard measures model performance on outcomes relative to the average model using a causal tracing methodology.

Exciting news: @AnthropicAI's Claude Opus 5 (Max) is #2# in Agent Arena, with Opus 5 (High) right behind at #3#, based on over 7K real-world agentic sessions. A strong debut: it slots in just below #1# Fable 5, and ahead of GPT-5.6 Sol (xHigh). Opus 5 Max is #2# with a net-improvement of 11.88%, and is #1# across both Confirmed Success and Praise vs Complaint signals. The default Opus 5 (High) is #3# with net-improvement of 11.73%, and by signal is #3# in Praise vs Complaint and #4# in Confirmed Success. In Agent Arena, we measure models on millions of real-world, long-horizon agentic tasks from a global community of users. Models can access web search, filesystem, and terminal tools to complete complex workflows. The leaderboard measures model performance on outcomes relative to the average model using a causal tracing methodology.

Grok-4.5 from @SpaceXAI debuts at #13# on the new Agent Arena leaderboard, based on 9.8K live agentic sessions. Compared to Grok 4.3, this release is a significant step forward in agentic performance (#29-#>#13#). It makes major gains on Bash Recovery, catching up to Anthropic and OpenAI models, and shows a substantial increase in confirmed task success, making it far more effective in real-world use. Check out rankings by signal below. Congrats to the SpaceXAI team on the strong Grok-4.5 release!

Code Arena just leveled up with fullstack capabilities 🚀 Introducing the new Fullstack Code Arena. We’re moving beyond frontend prototypes to fullstack development complete with databases, API keys, and fast deployments. Build, iterate, and ship real-world software — all in one place. Models now act as agents in the Code Arena, using structured tool calls to plan, execute, and refine in real time with real world tasks. Read more about it in the thread 🧵

Open-weight models are essential to a healthy AI ecosystem. Together with others across our industry, we are outlining a path for open-weight models to strengthen American competitiveness and expand economic opportunity, while protecting national security.

Hy3 by Tencent is #5# in Agent Arena for open-weight models (#25# overall)! It also ranks as the #2# open model in the Frontend Code Arena (#16# overall)! In Agent Arena: Hy3 lands at #25# overall (net -2.2%). Hy3 has strengths in tool-use (recovering well from CLI/bash errors, +2.6% and #25#), its biggest weakness is steerability as it struggles to course-correct when users push back, coming in at -7.1% (#30#). Agent Arena measures models on millions of real-world, long-horizon agentic tasks. Models get web search, filesystem, and terminal tools to complete complex workflows: writing code, creating slide decks, researching the web, building apps, and analyzing documents. We use causal tracing methodology to measure a model's net improvement, which indicates how much it improves outcomes relative to the average model. Below we break down how Hy3 scored across 5 key signals, drawn from tasks submitted by a global community of users. Here’s an overview on the signals: User-satisfaction proxies - Confirmed Success: an explicit "yes that worked" feedback from the user - Praise vs. Complaint: implicit sentiment in users reactions - Steerability: can the model course-correct when you push back? Tool-use proxies - Bash Recovery: how it recovers from CLI errors (primary signal for tool use) - Tool Hallucination: does it call tools that don't exist Congrats to the @TencentHunyuan team on this release!